import { QuotaError } from '../errors/mcpErrors.js';
/**
* Token Bucket Rate Limiter for Google Apps Script API
* Implements 100 requests per 100 seconds limit with buffer
*/
export class TokenBucketRateLimiter {
private tokens: number;
private readonly capacity = 90; // Buffer below 100 limit
private readonly refillRate = 0.9; // 90 tokens per 100 seconds
private lastRefill = Date.now();
constructor() {
this.tokens = this.capacity; // Start with full bucket
}
/**
* Check if request is allowed, throw QuotaError if not
*/
async checkLimit(): Promise<void> {
this.refillTokens();
if (this.tokens < 1) {
const waitTime = Math.ceil((1 - this.tokens) / this.refillRate * 1000);
throw new QuotaError(
'Google Apps Script API rate limit exceeded',
Math.ceil(waitTime / 1000)
);
}
this.tokens -= 1;
}
/**
* Get current token count (for monitoring)
*/
getTokenCount(): number {
this.refillTokens();
return Math.floor(this.tokens);
}
/**
* Reset bucket to full capacity (for testing)
*/
reset(): void {
this.tokens = this.capacity;
this.lastRefill = Date.now();
}
/**
* Refill tokens based on elapsed time
*/
private refillTokens(): void {
const now = Date.now();
const timePassed = (now - this.lastRefill) / 1000;
const tokensToAdd = timePassed * this.refillRate;
this.tokens = Math.min(this.capacity, this.tokens + tokensToAdd);
this.lastRefill = now;
}
}
/**
* Global rate limiter instance
*/
export const rateLimiter = new TokenBucketRateLimiter();
